This is an ancient Dutch-German surname which has two possible origins. Recorded in the spellings of Maas, Maase, Maass, (Dutch-German), and as Masi and Maso (Italian), and found as a patronymic or diminutive in almost all continental countries, examples being Masset (France) or Maesen (Flemish), its origins are either locational from residence by the River Maas which flows through the Low Countries, or occasionally as a nickname form of the Crusader introduced 'Thomas'. The meaning of the river name is probably 'marsh land', but this not proven. What is certain is that residential surnames in most of Europe form the largest single surname category. The development from 'Thomas' owes its origins to the Christian warriors of Europe who in the 12th century in particular, set out to free the Holy Land and specifically Jerusalem, from the Moslems. Although they failed, on their return they often gave their sons biblical names such as Thomas, Isaac and Abraham, in honour of their attempts. Later these names sometimes developed nickname forms, and subsequently these in turn became hereditary surnames in their own right. In England the name has been recorded since at least the 17th century. It may well be a Huguenot introduction, an example being Henri Maas, recorded at the church of St Mary at Hill, London, on March 7th 1689. In The Netherlands another example is that of Dirkije Maase, who married Renger Janse at Putten, Gelderland, on April 25th 1717, but the earliest example of all is in Germany, as shown in the curious recording below. The first recorded spelling of the family name is shown to be that of Mas Maas, which was dated 1407, in the charters of the (former) state of Pommerania, Germany, during the reign of Emperor Rupert 1 of the German Empire, 1400 - 1410. Surnames became necessary when governments introduced personal taxation. In England this was known as Poll Tax. Throughout the centuries, surnames in every country have continued to "develop" often leading to astonishing variants of the original spelling.